Tc‐99m depreotide imaging of I‐131‐negative recurrent metastatic papillary thyroid carcinoma

Abstract

The detection of radioiodine (I-131)-negative metastases of differentiated thyroid carcinoma (DTC) has been hitherto successfully tried by the well-known synthetic somatostatin analogue indium-111-labeled DTPA-octreotide (In-111 pentetreotide). The objective of this study was to evaluate the usefulness of scintiscan with the newer synthetic somatostatin analogue Tc-99m depreotide, in the restaging of papillary thyroid carcinoma (PTC) with detectable serum thyroglobulin (Tg) levels and negative I-131 whole-body scan (WBS). Whole-body planar and cervico-thoracic tomographic scintigraphy (single-photon emission tomography-SPET) with Tc-99m depreotide was performed in a 68-year-old male patient suffering from PTC stage III, with a mild increase in serum Tg levels coupled with a recent negative I-131 WBS. The findings were compared with those of neck ultrasonography (US) and computerized tomography (CT). Nodal neck dissection and histopathology provided the definitive diagnosis. Tc-99m depreotide scanning revealed foci of cervical lymph node metastases, which did not accumulate I-131. The findings were in accordance with neck US and CT. Histopathology established the diagnosis of metastatic cervical lymph node PTC. Lymph node immunoreactivity was positive for the somatostatin receptor subtypes 2, 5 and 3. Scintigraphy with Tc-99m depreotide could prove a useful adjunct to the armamentarium for the follow-up of PTC, especially in the setting of detectable serum Tg and negative I-131 WBS. ' 2006 Wiley-Liss, Inc.Key words: papillary thyroid carcinoma; metastasis; Tc-99m depreotide; I-131 whole-body scan Thyroid carcinoma (TC) is diagnosed in about 20,000 individuals in Europe each year and leads to 1,500-2,000 deaths annually. 1 It is the most frequent malignancy of the endocrine glands. However, well-differentiated TC (DTC) is a rare disease, accounting for less than 1% of all malignant neoplasms in humans. 2 The highest incidence rates are reported in countries with normal or even high dietary iodine status. The papillary subtype of DTC (PTC) comprises 60-70% of all thyroid malignancies, with a female-tomale ratio of 3:1. [2][3][4] In keeping with the literature, regional recurrence after total thyroidectomy ranges between 5 and 20% of the cases, while distant metastases develop in less than 10% and mainly involve the lungs and bones. 1 Lymph node metastases range from 35% to more than 70% in different series and are associated with higher rates of tumor recurrence. According to the 2002 TNM classification, their location, size, number and extension beyond the node capsule probably exert a prognostic impact. 1 However, recurrent PTC does not usually cause early symptoms; hence, prompt laboratory and imaging diagnostic accuracy is of the utmost importance.The determination of serum thyroglobulin (Tg) level has an established significant role in the follow-up and therapeutic decision-making of PTC after total thyroidectomy and thyroid remnant ablation with radioiodine (I-131); its detection indicates thyroid remnant, r...

Phosphonated chelates for nuclear imaging

“…Furthermore, the substitution of the carboxylate functions of the (2,6-bis[bis-((carboxymethyl)amino)methyl]pyridine 25 chelator (log K CuL = 15.69) by phosphonic units (L 1 ) stabilizes considerably the corresponding cupric complexes. Interestingly, L 1 forms more stable Cu(II) complexes (log K CuL 1 = 22.71 (7)) than its closely related analogues L 2 -L 4 . Indeed, the lack of one (L 3 , L 4 ) or two (L 2 ) phosphonic units is reflected by a destabilization of the Cu(II) complexes of about 3 orders of magnitude (log K CuL 2 = 19.5 (9), log K CuL 3 = 19.1(3), log K CuL 4 = 19.3 (6)).…”

“…Many radioisotopes are used for these two techniques, among them 64 Cu (T 1/2 = 12.7 h, β + : 17.8%, E β + = 656 keV; β − : 38.4%, E β − = 573 keV) is particularly promising for PET, [1][2][3][4][5] and 99m Tc (T 1/2 = 6 h, pure γ-emitter, E γ = 140 keV) is the radionuclide of choice for SPECT imaging. 2,5,6 Although these radionuclides can be used for their intrinsic properties, as in the case of thyroid imaging with 99m TcO 4 − , 7 the applications of 64 Cu and 99m Tc as targeted radiopharmaceuticals generally require the use of bifunctional chelates (BFC) designed to selectively bind the radionuclide and to be covalently linked to a bio-targeting vector such as an antibody, a peptide or a protein. The ideal BFC should form thermodynamically stable and kinetically inert complexes to prevent any ligand exchange reactions or hydrolysis in vivo.…”

Experimental study of 99mTc-depreotide eparation and its affinity with A549 cell

“…[ 99m TcO]depreotide binds to a wider range of somatostain receptor subtypes (SSTR2, SSTR3, and SSTR5) [2] than octreotide and its radiolabeled derivatives (mainly those binding to SSTR2) and, therefore, may be useful in diagnosing a broader range of tumor types. [ 99m TcO]depreotide has shown promise in the detection of a variety of tumors, including lung cancer [3] , lymphoma [4] , breast cancer [5] , thyroid carcinoma [6] , colorectal carcinoma [7] , and melanoma [8] . However, the labeling rate of 99m Tc depreotide under different conditions has not been defined clearly, and the mechanism of receptor binding with the tumor cell at different temperatures has not been clarified.…”

Η εφαρμογή του ραδιοεπισημασμένου αναλόγου της σωματοστατίνης ⁹⁹ᵐTc-depreotide στην διαγνωστική προσέγγιση του μεταστατικού καρκίνου του θυρεοειδούς

“…Με μικρότερη ευαισθησία, της τάξεως του 70-90%, ακολουθούν το 111 Ιn-Octreoscan, το 99m Tc-(V)DMSA, το 99m Tc-MIBI, και το 99m Tc-anti-CEΑ, ενώ 50-80% ευαισθησία παρουσιάζουν τα σπινθηρογραφήματα με 123/131 Ι-ΜΙΒG, 201 TlCl και 99m Tctetrofosmin [9]. Η αναφορά του Behr et al [130] Παράλληλα με τις δικές μας δημοσιεύσεις [164,165], πραγματοποιήθηκε μελέτη σύγκρισης της 18 F-FDG με το 99m Tc-depreotide, με ικανοποιητικά αποτελέσματα, που κατέληξε να χαρακτηρίσει τις δύο μεθόδους συμπληρωματικές [163].…”